Case Study
A fast-growing LATAM startup needed to replace its legacy infrastructure with a platform that could operate cost-effectively at scale. The business required automated, scalable processes to integrate with a wide range of national tax services — think Turbo Tax, but for their market. The existing system couldn't support the growth the company was experiencing. Every new customer added operational overhead, onboarding was slow, and infrastructure costs were growing proportionally with usage. The team needed a multi-tenant solution that would allow quick deployment of core infrastructure on customer accounts and dramatically faster onboarding — without rebuilding everything from scratch each time.A fast-growing LATAM startup needed to replace its legacy infrastructure with a platform that could operate cost-effectively at scale. The business required automated, scalable processes to integrate with a wide range of national tax services — think Turbo Tax, but for their market. The existing system couldn't support the growth the company was experiencing. Every new customer added operational overhead, onboarding was slow, and infrastructure costs were growing proportionally with usage. The team needed a multi-tenant solution that would allow quick deployment of core infrastructure on customer accounts and dramatically faster onboarding — without rebuilding everything from scratch each time.
Renaiss designed and built a cloud-native, serverless platform on AWS that replaced the legacy infrastructure with zero downtime. The architecture was multi-tenant from the ground up, enabling rapid deployment of core infrastructure on new customer accounts and dramatically faster onboarding.
Core functional components included user and admin authentication, payment gateway subscriptions, tax calculation and federal reporting, invoice issuance against federal systems, analytics, and automated alerts.
Full tech stack: AWS Lambda, DynamoDB, API Gateway, Cognito, SQS, SNS, SES, and S3 — orchestrated with Terraform and deployed through GitLab Pipelines, with a React frontend. Every component was chosen deliberately: Lambda eliminated always-on servers, DynamoDB handled variable workloads without performance degradation, and the SQS-driven architecture decoupled services so failures in one component didn't cascade across the system.
The impact was immediate and measurable. Infrastructure costs dropped 90% by eliminating idle server capacity and moving to a pay-per-use serverless model. The platform now supports more than 25,000 registered users and has processed over 200,000 invoices — numbers that would have stressed the previous architecture. And with CI/CD pipelines in place, the engineering team ships faster and with more confidence than before the migration.
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A platform built to grow — handling tens of thousands of users without adding infrastructure complexity.
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Federal tax reporting at scale, with the reliability that compliance-critical workflows demand.
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Serverless means paying for what runs, not for what waits. The savings were structural, not incidental.
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The legacy platform was replaced without interrupting service — no maintenance windows, no user impact.
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The legacy platform was replaced without interrupting service — no maintenance windows, no user impact.
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Auth, payments, tax calculation, invoice generation, analytics, and alerts — rebuilt cloud-native and production-ready.
Discovery & Architecture Design
01 / 05
Infrastructure as Code
02 / 05
Platform Rebuild
03/ 05
Zero Downtime Migration
04 / 05
CI/CD & Developer Experience
05 / 05
We mapped the existing platform's dependencies, compliance requirements, and pain points to design a serverless architecture that could replace it without disruption.
We provisioned the entire AWS environment using Terraform — making the infrastructure reproducible, version-controlled, and ready to scale from day one.
We developed the full product on AWS serverless services: authentication, payments, tax calculation, federal invoice submission, and alerting — with React on the frontend.
We executed the cutover from legacy to cloud-native with no service interruption, managing data migration and traffic routing so users never noticed the switch.
We implemented GitLab pipelines to automate testing and deployment, giving the team a modern release process and the velocity to keep iterating after go-live.
© 2026 - Renaiss with love
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